Chemoselective rhodium(II)–carbenoid cyclisation reactions in the stereoselective construction of rigidified cyclic α-amino acid derivatives
作者:Mioara Andrei、Jon Efskind、Trine Viljugrein、Christian Rømming、Kjell Undheim
DOI:10.1016/j.tetasy.2004.03.001
日期:2004.4
Intramolecular rhodium(II)-catalysed reactions in geminally disubstituted derivatives of the chiron (R)-2-isopropyl-3,6-dimethoxy-2,5-dihydropyrazine occurred with complete chemoselectivity at the adjacent annular nitrogen in preference to carbon–carbon double bond additions or C–H insertions. The products were four- and five-membered annulated rings, azetidin-3-one and pyrrolidin-3-one derivatives
Chiron(R)-2-异丙基-3,6-二甲氧基-2,5-二氢吡嗪的双取代衍生物的分子内铑(II)催化的反应在相邻的环氮上具有完全的化学选择性,而不是碳-碳双键键添加或C–H插入。产物是四元和五元环,氮杂环丁烷-3-酮和吡咯烷-3-酮衍生物。后者是制备季环状α-氨基酸衍生物的有价值的底物,其中α-季碳和氨基氮都嵌入吡咯烷环中,从而提供了新颖的α-季脯氨酸衍生物。环化反应中的五元环形成已通过单晶X射线分析进行了验证,四元环的产物已通过NMR进行了验证。